Andrew, the bearings have a small lip on them and the actual bearings are about 2 mm less in diameter than the outside diameter of the whole bearing which includes this small lip.

I inserted these bearing into a housing (two small sections of steel pipe) which was a snug fit for the inside diameter of the bearings, about 25mm.

These housings were slipped over a solid small length of steel rod which was attached to the main arm, exactly the same diameter as the inside of the bearings.

This rod was drilled through the center and tapped with a quarter inch thread, and a short 1/4 inch bold was screwed in to push up to the bearing, which in turn would fit snug and firm againt the main arm.

Both housing are the same, but the bottom one is attached as well to two round bits of steel plate and then drilled and tapped from the bottom up with a 3/8 thread which will screw to the existing tripod screw once the head has been removed.

Hope this helps a bit, maybe I should take it a part and photograph the procedure showing the construction, if I do I will post it here in a day or two.

Andrew, the bearings have a small lip on them and the actual bearings are about 2 mm less in diameter than the outside diameter of the whole bearing which includes this small lip.

I inserted these bearing into a housing (two small sections of steel pipe) which was a snug fit for the inside diameter of the bearings, about 25mm.

These housings were slipped over a solid small length of steel rod which was attached to the main arm, exactly the same diameter as the inside of the bearings.

This rod was drilled through the center and tapped with a quarter inch thread, and a short 1/4 inch bold was screwed in to push up to the bearing, which in turn would fit snug and firm againt the main arm.

Both housing are the same, but the bottom one is attached as well to two round bits of steel plate and then drilled and tapped from the bottom up with a 3/8 thread which will screw to the existing tripod screw once the head has been removed.

Hope this helps a bit, maybe I should take it a part and photograph the procedure showing the construction, if I do I will post it here in a day or two.

Leon

Leon - thank you, I appreciate the explanation. And if you do get the chance to take a couple of photos, even better!

Kerrie, Adam, and others, many thanks for your kind words, it is great to be able to fiddle around in the shed and come up with something half decent and workable.
I get a great sense of satisfaction, especially when it works.